My Suzuki RG125F Project

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Still trying for that first start I'm afraid. The no spark problem turned out to be the CDI box, after much searching I tracked down a replacement in France, fitted that and replaced the coil while I was at it. Presto, a spark!

I stripped and cleaned the carb so there should be no fuelling issues, however the spark plug isn't wet when I take it out after trying to start it. I have finally performed a compression test and got 100 psi. Everything I can find suggests I should be getting a minimum of 110 psi in a healthy engine. It would explain no fuel too, as with no compression the fuel won't be drawn into the cylinder.

So as far as the holy trinity of fuel, spark and compression goes, it appears she had... none of the above. Is there any way to tell if the compression problem is being caused by the piston rings or the crank seals? The rings looked OK when I pulled the cylinder off, crankshaft seals will mean pulling the motor out again and completely disassembling it, which I will do but only if necessary.

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Steve Bass said:

But if you're refreshing a motor, new rings should be a given...

Yep. Given that the piston looked brand new (see pics earlier in the thread) I assumed the rings must be good. Chalk that one off to experience I suppose. I am going to test for loss of compression from the cylinder head and inlet manifold too though. I'll get new rings, see what that does for the compression, then one way or another it's back to the carb to see what it's having a huff about.